Tetanus toxin: a marker of amphibian neuronal differentiation in vitro.

Tetanus toxin may be used to specifically mark neurones in cultures of mammalian and chick nervous tissue. We have prepared cultures of neural ectoderm and underlying mesoderm from late neurula Xenopus laevis embryos, and shown that in this Amphibian species, neurones are labelled by tetanus toxin. Aggregate cultures of ectoderm and mesoderm from late blastula embryos were than examined to determine whether tetanus toxin might be used to mark neuronal precursor cells. Our observations suggest that this is not possible; neurones are seen to have acquired tetanus toxin receptors only after they have become morphologically differentiated.